Plastic containers such as bottles of water are manufactured and filled according to different methods including blow molding or stretch-blow molding.
According to one of these known methods a plastic preform is first manufactured through a molding process and then heated before being positioned inside a blowing mold.
The preform usually takes the form of a cylindrical tube closed at its bottom end and open at its opposite end.
Once the preform has been positioned within the mold only the open end of the preform is visible from above the mold.
A liquid injection head comprising an injection valve is brought into a sealing engagement with the upper surface of the mold around the open end of the preform.
The above-mentioned method makes use of a stretch rod which is downwardly engaged into the open end of the preform so as to abut against the closed bottom end thereof. The stretch rod is further actuated to be urged against the closed end, thereby resulting in stretching the preform.
After the stretching phase has been initiated a liquid is injected into the preform through its open end thanks to the injection head, as disclosed for instance in Applicant's patent EP 1 529 620 B1. Upon command, the injection valve is caused to be opened, thereby enabling flow of liquid therethrough and injection of liquid into the preform. This liquid injection causes expansion of the preform until coming into contact with the inner walls of the mold, thereby achieving the final shape of the bottle.
Once the bottle has been blown and filled with liquid, the injection valve is caused to be closed.
The Applicant has noticed that a certain amount of liquid (residual liquid) is still present in the space located between the closed injection valve and the bottle.
When the injection head is lifted up and/or the mold is opened to remove the blown and filled bottle residual liquid that has accumulated within the above-mentioned space splashes all around and, therefore, is wasted.
Also, liquid spreads all over the inner walls of the mold.
Liquid drops which are present on the mold inner walls have to be removed before accommodating a new preform inside the mold. Otherwise, the presence of liquid drops may impair defects in the outside surface of the next blown and filled container.
It is to be noted that the above situation also arises with other blow-molding methods and for other kinds of containers.
There is therefore a need for an apparatus remedying at least one of the above-mentioned drawbacks.